This is kind of a kicking-a-dead-horse discussion, because as others have pointed out, "autopilot will fly you into a mountain" (complete with warnings).
But does the average driver know that? It is their perception that's important here. The Utah driver expected the car would not fly her into the mountain, so to speak. Naming, marketing context of self driving alongside this feature, and driver instruction are all likely part of the puzzle.
If you think the name has nothing to do with it, would you also say that if it had the name "Deluxe Cruise Control" people would treat it the same? I'm not so sure about that. Engineers maybe.
I agree that the name issue is a red herring, but not for this reason. Autopilots are operated by people who are trained in their use, and, for the most part [1], understand their limitations. 'Understanding their limitations' is exactly the issue here.
[1] Following a number of WTF-type accidents, there is some concern that airplane automation has become too complex for pilots to reason about when it partially fails, but if that is actually the case, it raises the bar for all partial automation, including for cars.
If you think the name has nothing to do with it, would you also say that if it had the name "Deluxe Cruise Control" people would treat it the same? I'm not so sure about that. Engineers maybe.